When Chicago police officers moved in to arrest Occupy Chicago protesters in Grant Park on a recent weekend, they did not swarm the crowd of hundreds to handcuff people en masse.

Instead, a group of officers approached each demonstrator with a choice: leave immediately with no questions asked or be arrested.

It took hours, but one-by-one, the protesters stood up calmly to be handcuffed and were led to jail. The few who resisted did so passively, refusing to stand, compelling officers to carry them away. There seemed to be an unspoken agreement between police and protesters: This demonstration was going to be peaceful.

While resulting in hundreds of arrests, the protests in Chicago's financial district during the past two months have not been marred by spates of violence that have plagued other Occupy sites, such as in Denver, New York and Oakland, Calif.

Police, protesters and experts have myriad ideas why Chicago has avoided clashes. But chief among those are that Chicago's demonstrators say they continually pledge nonviolence, and Chicago police say they'll protect the protesters' right to demonstrate, so long as laws aren't broken.

"A lot of people believe that standing up and doing something peacefully takes a lot more courage than violence," said protester Ashley Edwards, 19, of Pilsen. "Violence just brings everyone down. Anyone who doesn't agree with that isn't really welcome."

"We treat every First Amendment expression fairly and equally, but we have to balance it with our concern for public safety," Chicago police spokeswoman Sarah Hamilton said. "We've tried to do everything we can to protect their First Amendment rights while also enforcing the city laws."

The delicate balance struck between police and protesters could be seen at a recent demonstration, where officers monitoring the protesters downtown were seen chatting casually with protesters. The officers wore regular uniforms instead of riot gear, Hamilton said, because there has been no safety threat that would require more protective equipment.

For their part, Occupy Chicago protesters start every general assembly with a pledge of nonviolence. At one protest, volunteers could be heard relaying instructions from police to stay out of the road during the march. They then stood alongside the officers who lined the protesters' path, keeping everyone on the sidewalk and out of traffic.

"We respect their rights. They respect the job that we have to do," Hamilton said. "They've been very compliant. If there's something blocking the public way, our officers will tell them that and say, 'Please move this.' And they do."

Mayor Rahm Emanuel has kept a watch on the department's handling of the protests, talking with Chicago police Superintendent Garry McCarthy before arrests during one demonstration.

More than just garnering local attention, Chicago's handling of the demonstrations could be of international concern, a primer for how the city will handle protesters expected at the G-8 and NATO summits scheduled in May, political analysts have said.

Chicago also has to contend with the stigma of the bloody riots at the 1968 Democratic National Convention that tainted Mayor Richard J. Daley's image.

Still, there have been minor confrontations. About 300 people were arrested in recent weekends for trying to remain in Grant Park after the park closed. Those incidents remain a sore spot for protesters, but it was not unexpected. Hours before the arrests, police warned demonstrators on a loudspeaker that they were breaking the law, and a legal representative for the protesters gave speeches on how to be taken into custody peacefully.

The protesters had divided themselves into color-coded groups, with the "green" group declaring itself ready to be taken to jail.

Other cities haven't fared as well in keeping the peace.

Stephen Duncombe, associate professor of media and culture at New York University, said that the Occupy Wall Street protesters there seem to interact well with police officers at their home base in Zuccotti Park but that things have fallen apart outside the encampment, resulting in 700 arrests on the Brooklyn Bridge and the transfer of one police commander who used pepper spray on demonstrators.

Duncombe said authorities have been "very clumsy" in the way they've tried to control the protests.

"The Bloomberg administration has a history of relative incompetence when it comes to protests," Duncombe said of New York Mayor Michael Bloomberg. "They tend not to know how to deal with large demonstrations."

In Oakland, about 100 protesters were arrested during a demonstration Oct. 25, where police used tear gas and beanbag rounds to disperse the crowd. One Marine veteran suffered a skull fracture, reportedly when a police projectile hit him in the head.